Add strongly typed messages in protocol

[lachem]

• introduce message hard types in protocol
• compute 32 bit hashes for each type schema
• expose generated hashes in dynamic, json and cpp
• improve formatting of the generated cpp code
• allow looking up specific dynamic serializer by type
• add schema hash collision validation

The introduction of hard types for messages in the
generated protocol is dictated by the ease of use.
Attempting to have a message data (type) and
pure message (type_id + proto_id) did not result
in an ergonomic API. Instead message had to be
always provided alongside the type. Messages
inherit from data types as it is much easier to create
and send them this way. Messages remain purely
informational and hold no data on their own outside
of the data inherited from the type they are based on.

The introduction schema hash (TYPE::HASH in C++,
serializer.type_hash() in Python and ["hash"] in json)
is dictated by the need to support type consistency
checks of serialized messages.

Since the extraction of types from protocols the latter
became just logical grouping of types. In fact the name
or id of the protocol is not needed to successfully
serialize / deserialize a message.

[DrTon]

Generating types and protocols maybe?